#!/home/luyanfei/.local/bin/checkio --domain=py run remove-brackets

# Before solving this mission, you can try to solve the"Brackets"mission.
# 
# Your task is to restore the balance of open and closed brackets by removing unnecessary ones, while trying to use the minimum number of deletions.
# 
# Only 3 types of brackets (), [] and {} can be used in the given string.
# 
# Only a parenthesis can close a parenthesis. That is. in this expression "(}" - the brackets aren’t balanced. In an empty string, i.e., in a string that doesn’t contain any brackets - the brackets are balanced, but removing all of the brackets isn’t considered to be an optimal solution.
# 
# If there are more than one correct answer, then you should choose the one where the character that can be removed is closer to the beginning. For example, in this case  "[(])",  the correct answer will be "()", since the removable brackets are closer to the beginning of the line.
# 
# Input:A string of characters () {} []
# 
# Output:A string of characters () {} []
# 
# 
# END_DESC

def remove_brackets(a):
    # your code here
    return None


if __name__ == '__main__':
    print("Example:")
    print(remove_brackets('(()()'))

    # These "asserts" are used for self-checking and not for an auto-testing
    assert remove_brackets('(()()') == '()()'
    assert remove_brackets('[][[[') == '[]'
    assert remove_brackets('[[(}]]') == '[[]]'
    assert remove_brackets('[[{}()]]') == '[[{}()]]'
    assert remove_brackets('[[[[[[') == ''
    assert remove_brackets('[[[[}') == ''
    assert remove_brackets('') == ''
    print("Coding complete? Click 'Check' to earn cool rewards!")